We originally modeled the added fee after Phoenix, who charges 0.4% + 4 sats. However, we’ve updated it so that anything under 50 sats incurs a 1 sat extra fee; 51–1000 sats is 2 sats + 0.4%; and anything greater than 1000 sats is 0.4% + 4 sats.

Zaps are cool so we shouldn’t have added a large fee to micropayments.